Help your child learn percents, a key topic in middle school math problems!

Your child needs to learn percents to handle many everyday math situations she or he will encounter as he grows into adulthood; however, percents are a puzzling topic in the math curriculum.

Students normally learn how to do percentages in middle school math problems, typically in the 7th grade math curriculum. Sometimes they’re touched on again briefly in Algebra 1, and then scarcely seen again in the high school curriculum.

Yet, as far as everyday math, in the regular grown-up world, they are encountered as much as any other math topic besides basic arithmetic.

To understand why it’s important to learn percents, just think of how often we encounter them in everyday life:

• In the marketplace (sales, discounts, sales tax, tips)


• In business and economics (inflation rate, taxation rates, unemployment rates, and so on)


• Personal finance (CD rates, bank account rates, mortgage rates, investment rates, etc)


• And many more examples

And that’s the strange part. We learn percents when we’re too young to understand how they work, and why we need them. As a result, many people are left as adults really needing to understand how to do percentages to get along, but not always completely sure of what they mean and how to work with them.

So, here’s the basics of the concept of percents and why we need to learn percents.
In our number system, we have three styles or ways of writing fractions. A fraction means a part of a number. The oldest way is what is called a common fraction, usually just called a fraction. For example: 1/2,2/5,7/10, etc.

In the 16th century, the system of decimal fractions was devised. In everyday English, usually just called decimals. For example: 0.3, 0.15, 0.009. These are fractions too, as they are pronounced: “three-tenths”, “fifteen hundredths”, and “nine thousandths.” This system was devised to make certain arithmetic operations easier, most dramatically, addition and subtraction.

With common fractions, you need to find a common denominator to add or subtract. With decimals, you just need to line up the decimal points, which automatically achieves this.

Now what about percents?
Percents are the third form of writing fractions. In many contexts where fractions are being used, it is most convenient to give the fractions all with the same denominator. That way, the fractions can instantly be compared.

From a student’s perspective, the most obvious example is grades. If test grades were given as common fractions, for example: 17/20, 8/10, 12/15, it would be hard to compare those grades to understand which are better, or to observe a trend.

However, if the fractions all have the same denominator, then we can just focus on their numerators, and see which were bigger or smaller. When we make the denominator of these fractions “100”, we turn them into percents. Percent is derived from the Latin words meaning “out of 100”.

When we write 85%, we simply mean 85/100. The percent symbol ( % ) is just a stylized form of /100. The diagonal bar represents the fraction bar, and the two little circles represent the circles of 100.

Here are a few examples of how to do percentages that you might encounter in typical middle school math problems and also in everyday life.

Investments:
Savings accounts and some checking accounts earn interest, which is calculated as a percentage. I recently opened an interest-earning checking account, though it was only when I received my first statement that I realized what the interest amount was. It is 0.05%.

That means that to calculate the interest earned, you would multiply 0.05% x the account balance. So for example, you would need to learn percents to be able to calculate your expected interest.

If there were $2000 in the account, the calculation would be 0.05% times 2000.

Example: 0.05% x 2000

0.05/100 x 2000/1

$1 (That's for the whole year, each month would only be 1/12 of that)

Here’s a confusing, but important example for civic responsibility:
Let’s say the unemployment rate is 9.8% one month, and another month it’s measured at 10.2%.

Sometimes in the news this situation is described as a 0.4% change.

However, that’s not the normally understood meaning of percent change.

Normally, the percent change is what you would multiply the original number by to get the given change.

In this case, the equation would be:

Example: p x 9.8 = 0.4

p = 0.4/9.8

p=~.041 ,which as a percent equals about 4.1%

So the change in percent was 0.4 percent, but the percent change is actually more than 4%.

A 4% change in such an economic measure, in one month, is a dramatic and significant change, so it’s important, as a voting citizen, to understand the difference!

I hope this brief presentation helped you to understand why students need to learn percents, identify percents equations as they might appear in 7th grade math problems, and also to clarify what percents are.

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